GPSA Ch. 16
| Parameter | Typical Range |
|---|---|
| Flash Pressure | 50–200 psig |
| Flash Temperature | 100–200°F |
| Retention Time | 3–10 min |
| L/D Ratio | 2.5–4.0 |
| KSB (Flash Drum) | 0.10–0.20 |
| Vapor Fraction | 30–80% |
Rachford-Rice Flash Equation:
Solved iteratively for vapor fraction V/F. K-values depend on component volatility and pressure ratio. Methane and ethane preferentially flash; propane and heavier remain in liquid.
Function: The hot rich-oil flash tank liberates dissolved light gases at reduced pressure before the oil enters the purification still. This reduces vapor loading on the still and recovers fuel gas.